lightning protection

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Re: lightning protection

Postby jwv630 on Wed Dec 10, 2014 6:00 pm

Hey Fellow Builders:

There's an interesting article in Small Craft Advisor magazine this month (Jan/Feb 2015) titled 'Lightening Protection for Small Boats'. No pearls of wisdom but some confirmation of the discussion on this topic.

Closed up the boatyard (garage) for the winter here in Baltimore. Garage is quite large and it's difficult to get it up to the +/-70 degrees needed to work with the epoxy and fiberglass. Started building a pair of oars for my Skerry which is quite a challenge and fun; bought the plans from CLC. Maybe start a bench project for PS too.

Warm regards and Merry Christmas
Jimmy V
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Re: lightning protection

Postby DanaDCole on Thu Dec 11, 2014 11:53 pm

Thanks for the heads up. I have that issue but haven't read through it yet--didn't realize that topic is in it.

On the garage-warming note, MAS says in their literature that 55 and up is OK for laminating fiberglass and 45 and above is OK for bonding. I keep my garage at around 50 for most work and bring it up to 55-60 for fiberglass work. At that temperature I usually mix medium hardener, although I have mixed slow and it cured just fine. One thing I like about the lower temperatures is that I have a nice window of time before applying subsequent coats. I usually get around to applying the wetting-out coat sometime around mid-afternoon. I put on the fill coat in the late evening, and I can wait until the next morning for the gloss coat. No sanding required. I really like that feature of MAS epoxies. You can apply subsequent coats as soon as it acquires tack, and you have until it approaches "thin-film set" to get a good chemical bond and no sanding required until all three (or more) coats.
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Re: lightning protection

Postby jwv630 on Sat Dec 13, 2014 2:35 pm

Hi Dana:

Many thanks. You are absolutely correct on the minimum recommended temperature requirements for the MAS epoxies. I just had to go to MAS's website to double check (sorry). Here's the link to their Frequently Asked Questions page; good stuff there: http://www.masepoxies.com/faq##23

The 'but' is that I clearly recall John Harris/CLC telling me that the minimum temp for using the MAS epoxy to wet out fiberglass should be at least 70 degrees; 80 degrees better. This is the primary reason I shut down for the winter...Hmmm. Perhaps I'm mistaken and will email him this week to get clarification. I'll report back whatever I find out.

Enjoy your thoughtful comments on the forum. Thanks....
Jimmy V
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Re: lightning protection

Postby John C. Harris on Tue Dec 16, 2014 9:47 am

60 degrees F is CLC's official lowest-recommended temperature for working with ANY epoxy of ANY brand. See page 4 of the PocketShip manual.

The epoxy makers (and some kits-and-plans sellers), sensitive to the prospect of lost sales during the cool months, overstate the ability of their products to perform in cold shops. They can argue with me if they want, but my nearly 30 years of working with marine epoxy counts for something, and they can eat my shorts. Epoxy involves an exothermic reaction; the chemical reaction generates heat that is essential to creating a full-strength cure. At low temperatures, my experience is that epoxy simply creates weaker bonds. I've been able to pop apart joints glued in cold temps that would have been immovable if cured at room temperature.

There's another problem with cold shops and cold epoxy: what it does to viscosity. Cold epoxy is viscous, making it difficult to "wet-out" fiberglass. Smart builders keep their epoxy jugs warm with a light bulb, but that alone is not enough. If you bring warm epoxy and spread it on a 50-degree hull, the epoxy chills upon contact. The viscous epoxy also fails to penetrate the wood effectively, which is sorta the whole point of using epoxy is this context.

With a roll of polyethylene plastic and a couple of space heaters, it is WAY easier to warm your space than it is to fight to get epoxy to cure at 50 degrees or whatever. Here's an article on cheap, effective ways to get through the winter in an unheated shop: http://www.clcboats.com/shoptips/epoxy_ ... ather.html

Point a light bulb at your jugs of epoxy and keep the goo well up into the 70's or 80's F. When you're working on your boat, the surface temp needs to be at least 60 degrees F.
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Re: lightning protection

Postby DanaDCole on Tue Dec 16, 2014 12:03 pm

Thanks John, always very grateful for the voice of experience!

OK, I get the point about epoxy sales. BTW, my epoxy jugs are stored in the utility room adjacent to the garage at about 75 degrees. Also, although MAS says 55 is OK I have always done my laminating work at 59 or higher--so I'll increase the minimum by 1 degree. :)

I am glad to hear 60 degrees is OK, though, because it gives me more time to work, especially on larger areas. And like I said I can only work with epoxy from late fall to about mid-spring because otherwise it gets too hot here and I've had bad experiences with the epoxy kicking before I had a chance to smooth it out. And this was at a time when it wasn't all that hot (by Oklahoma standards), about 87 or 88 degrees.

I guess this is where the "epoxy sales" argument is valid at the other end of the scale--MAS claims a pot life of a little over 17 minutes at 86 degrees and 11 1/2 minutes at 95 degrees, so I should have had at least 15 or 16 minutes of pot life. Not so! I had about 3 minutes at most, and no, I didn't mix up a huge pot, I had mixed about 6 ounces of epoxy and added wood flour to that (lost perhaps 3 minutes of pot life while mixing--also the epoxy was cooler, about 75 deg.). The lesson I should have learned is that if you cannot trust them on the high end, why should you trust them on the low end? (I have printed out their chart and posted it in my garage, but I'm going to modify, then re-print it.) Other than this, I love MAS products--much easier to work with than other brands in my limited experience.

So the bottom line as I see it seems to be a relatively small temperature window to work with (about 60 maybe 80 deg. F) unless you have the luxury of a heated and air-conditioned shop.
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Re: lightning protection

Postby jwv630 on Wed Dec 17, 2014 12:09 pm

Hi John:

Many thanks for your reply and expertise. I always receive great service from CLC and buy all my supplies/tools from you guys in support. By the way, great article in Chesapeake Bay Magazine this month on CLC; many congrats....

Jimmy Vitale
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